This invention relates to a novel system for applying an antifouling layer or layers of copper or copper alloys to boat and ship hulls. Historically, attempts to control antifouling were by the use of lead sheets attached to the hull, later followed by the application of copper sheathing. With the advent of larger ships, steel hulls and fiberglass hulls, not only the attachment of copper sheathing became impractical but the additional weight and cost resulted in the promotion and development of antifouling paints and leach out gradually to provide the antifouling properties.
A hull that is not protected will soon have marine organisms adhering and growing on its surfaces. This growth will not only add weight but, of more economic importance, will increase the surface roughness, thereby reducing its speed, and increasing power consumption. In the case of commercial vessels, outage for painting of a hull means loss of income as well as labor and material cost increases.
The present state of the art is that the paints or coatings consist of two parts, a binder or vehicle which holds the toxin or biocide for the duration of the toxicant and the toxicant or biocide which actually controls and prevents the antifouling. These are formulated so as to dissolve uniformly at the same rate so that as the binder erodes or is washed away, new surfaces with the biocides are exposed, therefore as long as the coating has not eroded away, there is antifouling action present and antifouling performance is proportional to the thickness of the coating applied.
A Chilean patent, which has been tried in the Annapolis area, consisting of applying tiles of copper foil with preplaced adhesive on the foil itself to the hull, was abandoned because of adhesive problems.
Another similar effort was published in Cruising World Magazine, September, 1982, pages 122 et seq. in which case the adhesive is applied directly to the hull followed by the copper alloy foil. This method, though sound in concept, is very labor intensive in that there is considerable tailoring necessary to fit not only the layers of adhesive, but also the panel or tiles of copper foil over the complex compound curves of hulls.
U.S. Pat. Nos. 4,234,340 and 3,661,506 both review the vast spectrum of antifouling systems and schemes which, to date, have not been commercially successful. A survey of antifouling paints is set forth in Cruising World Magazine, February, 1983, pages 121 et seq.
In summary, the most modern paint and coating technology depends on uniform consumption of the binder and toxin or biocide and therefore are limited by the thickness or number of coatings applied. Secondly, the tile or foil method, with its painstaking tailoring of individual strips or tiles to the complex hull surfaces has not been readily accepted by the marine trades